Device for anchoring the foundation of a structure in the ground

ABSTRACT

Device for anchoring the foundation of a structure in the ground comprising an anchor (1) and a pull line (8) along an axis (ZZ&#39;), the end (19) of a terminal portion (18) thereof being integral with a fastener (9) secured to the body of the anchor (1). The body comprises a front wing element (2) shaped to go into the ground along an axis (XX&#39;) and a rear wing element (3) opposing the pull of the line (8) by abutment in the ground once the anchor is tilted in the ground. In one embodiment, the fastening location (9) is offset to the axis (ZZ&#39;) of pull in the direction of the axis (XX&#39;) of the anchor body (1). The anchoring device comprises a component (7) for guiding the terminal portion (18) of the pull line (8) between the fastening location (9) and the axis of pull (ZZ&#39;), whereby the fastener is offset. The anchor body (1) comprises a fin-shaped element (6) located on the other side of the plane of the front wing element (2) in relation to the guide component (7).

The present invention relates to a novel device for anchoring thefoundation of a structure in the ground.

The technical field of the invention is the field of making groundanchors that are forced into ground of any kind, whether from thesurface of the ground or from a wall in an underground gallery or thelike, by pile-driving, vibrosinking, pile-jetting, etc. After they havebeen forced to a certain depth or distance from said surface, suchanchors have traction applied to them from said surface by means of atraction device which may be a cable, a chain, a belt, or otherdeformable rod providing its connection with the anchor is flexibleand/or hinged, thereby causing said anchor to tilt into a position whereit extends transversely to the traction direction thus enabling it toresist said traction by opposing a maximum surface area of its wing unitthereto, thereby holding the traction device against such traction forceup to a certain value.

As in all known devices of the same type, the main applications areanchoring pegs for stays, for cables, for foundation masses, forstructure-supporting plates, etc. . . . and more particularly when it isdesired to obtain foundation strength even when the ground itselfpresents poor resistance to traction, thereby creating a foundation massconstituted by the ground itself which is prestressed for that purpose,as taught in European patent EP 317458, published on May 24, 1989 andfiled by T.S.I., and which also describes the entire technique forimplementing foundation anchoring, the principles of which are thereforeknown and are not recalled herein.

Numerous other devices are known that enable anchoring to be provided inthe ground in the manner described above when describing the technicalfield of the invention, even when there is no question of making a massconstituted by putting the ground itself under prestress which is thesubject matter of the above patent; some such anchor devices have beenthe subject of patent applications, in particular for devices that arerequired to tilt or incline the anchor: by way of example, mention canbe made of French patent application FR 2 470 823, published on Jun. 12,1981, in the name of Mr. Pierre CARGIOLLI, which describes a device forloose ground that enables the anchor to be tilted by placing theattachment point of the anchor line in front of the center of itssurface area so that, when tension is applied, because of the greaterarea of the rear portion of the wing unit, the opposing force from theground applied to the rear portion is greater than that applied to thefront portion which therefore rises. Nevertheless, that method is notreliable since the anchor can rise a great deal and can even come out ofthe ground before the rear portion of the wing unit has been able tocome into abutment so that the intended process can take place: thismeans that the anchoring device is not always at its design depth.

To avoid the above uncertainty, European patent application EP 161190published on Nov. 13, 1985 in the name of I.F.P. places a flap hinged tothe rear of the anchor wing unit for causing blocking to start morequickly prior to tilting. Nevertheless such a device cannot prevent theanchor being raised through a non-negligible distance when tension isapplied, particularly in cases where a leader hole is made by means ofan auger in order to facilitate pile-driving: a portion of the flap isthen in air and its abutment action is reduced and delayed. In addition,given the forces involved, the hinges of the flap can break. Also, whilethe anchor is being driven down, material can jam between the flap andits abutment, preventing it moving and thus preventing it fromperforming its function. That reduces to the previous case.

Mention may also be made of British patent GB 2089862 published on Jun.30, 1982 in the name of E.G. WISE which describes a hinged device foroperating, after driving, to tilt the wing unit by rotation about a pinthat is kept disengaged by the thrust force from the driving rod priorto changing position by rotation through 180°: that device iscomplicated and cannot be reliable on site.

Finally, various anchoring systems are known that include ribs andblades on the front portion of the anchor to facilitate driving them inthe desired direction, in combination with systems for hinging the pointof traction that is offset from the driving axis of the anchor, firstlyto keep the cable apart from the driving rod so as to avoid damage tothe cable, and secondly to facilitate tilting of the anchor after it hasbeen driven: such a device is described, for example, in European patentEP 313936 published on May 3, 1989 in the name of FORESIGHT INDUSTRIES,INC.; nevertheless, even if control over driving direction in the groundis thus indeed more effective, pivoting of the anchor itself in theground is not improved, at least not at the desired depth, and it doesnot take place in reliable manner.

Thus, it has been observed that most present anchors, unless they areassociated with complex devices that are mechanical and themselves notvery reliable and/or complicated to implement, do in fact often risewithout tilting, even so far as to come out of the ground, when atraction force is applied on the anchor line that connects them to thesurface: tilting and blocking take place in a manner that is more orless reliable only in ground capable firstly of closing up behindanchors after they have passed through it, and that is also ofrelatively high density; this restricts situations in which such anchorscan be used. In clayey type ground that is too compact, the path openedup by the anchor remains open behind it, and in muddy type sands thatare too soft known anchors do not tilt immediately or even do not tiltat all when subjected to traction, thus causing them to rise too farand, naturally, making it impossible to guarantee anchoring depth.

Unfortunately, when it is desired to ensure that anchoring is performedproperly, particularly in an application to prestressing the ground asdescribed in above-mentioned patent EP 317458, it is necessary to becertain that tilting takes place at the intended depth in order toguarantee that there exists the necessary volume of ground forconstituting the foundation mass, and this applies regardless of thenature of the ground, given that anchoring depth is a function thereofand of the force that it is to withstand.

The problem posed is therefore to be able to make an anchoring devicethat comprises an anchor and a traction line, which can be implementedessentially to ensure that the anchor tilts as soon as it has reachedthe desired depth so as to be sure that anchoring takes place at a givendepth and that this applies in any type of ground; another object of theinvention is to enable said anchor to be driven into the ground whilecontrolling the direction thereof and without any risk of majordeflection.

A solution to the problem posed is a device for anchoring the foundationof a structure in the ground, the device comprising an anchor and atraction line along an axis ZZ' that is preferably offset from the axisXX' of the anchor, with the tip at one end of the line being secured toan attachment piece or point which is fixed to the body of the anchor,which body includes a front wing unit shaped to penetrate into theground along its axis XX', and a rear wing unit for opposing the effectof traction on said line by coming into abutment in the ground after theanchor has penetrated therein by being driven along its axis XX' andthen tilted; according to the invention, the anchor device includes aguide and bearing piece for guiding and supporting said end of the linerelative to the body of the anchor between said attachment point and thetraction axis ZZ' of the line, and said anchor body includes a finsituated on the other side of the plane of the front wing unit relativeto said guide piece, enabling desired tilting to be started morereliably.

In an embodiment in which the traction line is deformable, e.g. a cable,with said attachment point for the traction line being offset from thetraction axis ZZ' thereof towards the axis XX' of the body of theanchor, said guide piece performs said offsetting and is a portion ofthe body of the anchor on which said end of the traction cable or linefixed to said attachment point bears.

In another preferred embodiment, in particular when the depth ofanchoring is shallow, of the order of less than 1 meter, as in an urbanenvironment and for limited traction forces, said guide piece isconstituted by a rigid piece that forms the end of the traction line,which is hinged about said attachment point, and which bears against thebody of the anchor via a spring housed therein and which, in the drivingposition, is compressed between the rigid end of said traction line andsaid body of the anchor. The traction line may itself be entirely rigid,and thus a single piece, being hinged directly in the body of the anchorabout an attachment point secured to the end thereof, e.g. in the formof a stub axle which may either be in line with the traction axis XX' orelse be offset relative thereto, the end of the rigid piece thenincluding a bend.

In an embodiment that may include one of the embodiments mentionedabove, said anchor also includes another fin for protection purposesdisposed in front of said guide piece perpendicularly to the plane ofthe front wing unit and extending over a height h relative thereto,where h is greater than the distance through which the axis ZZ' of saidtraction cable is offset relative to the front wing unit of the body ofthe anchor; preferably, said fins, referred to respectively as a"protection" fin and as a "tilting" fin, are symmetrical about saidplane of the front wing unit, are identical, and are both situated infront of said guide piece.

The result is novel devices for anchoring the foundation of a structurein the ground comprising an anchor as defined above that makes itpossible to solve the problem posed and that achieve the objects of theinvention, which was not possible with devices known in the past.

One of the major novel and original points of the present invention isto define clearly the connection between the end of the anchor line andthe anchor itself in a position that is well determined, whereas untilnow all known anchors have, on the contrary, included connections thatare flexible and free, without guidance and without forced support,since attempts have always been made to keep the traction line inalignment with its attachment point on the anchor as soon as tension isapplied; that completely prevents creating a deliberate thrust force Rextending transversely to the traction direction ZZ', as can be seen inparticular in illustrative FIGS. 2 and 8 as described below, thus makingit possible in the present invention to obtain instantaneous pre-tiltingof the anchor, either as soon as tension is applied to the tractionline, or else as soon as the driving rod is removed, and with this beingtrue regardless of the nature of the ground. Numerous tests havedemonstrated that anchors of the invention enable said tilting to beobtained at the desired depth, which is not possible with prior artdevices; such known devices have not sought to achieve such accuracyconcerning depth since the essential purpose of such devices has been toobtain anchorage to withstand a traction force without taking thecontribution of the surrounding ground into consideration, whereas inthe present case, in order to apply anchoring as defined in Europeanpatent EP 317458 mentioned in the introduction, anchoring depth isessential for obtaining sufficient contribution from the ground and thusfor withstanding a given force.

Thus, in the examples described below, it will be observed that the endof the anchor line is always deliberately brought into contact with thebody of the anchor by means of a guide and bearing piece, eitherdirectly or via an intermediate spring, which piece is one of theessential elements of the present invention, whereas in known anchorlines, even those that are hinged or offset relative to the axis of theanchor, the only force transmitted to the body of the anchor is a forcein line with the direction in which tension is applied, withoutprovoking a transverse reaction force on the anchor.

In addition, the presence of the fin that may be referred to as a"pre-tilting" fin, as mentioned above, which fin extends perpendicularlyto the plane of the main wing unit of the anchor and is situated on theother side thereof relative to the traction line, it becomes possible,not only to achieve better guidance while the anchor is being driven ina given direction, but also to establish a heel that comes into abutmentalmost immediately as soon as the traction force begins; this generatesa genuine and immediate pre-tilting torque on the anchor in combinationwith the specific disposition of the anchor line in accordance with theinvention, as shown in the embodiments of FIG. 2 or of FIG. 8, and withimplementation thereof being shown in FIGS. 7 and 11 below.

In known anchors, the moment of tilting as constituted solely bytraction being applied to the lever arm formed by the traction linebeing offset from the axis of the anchor is not sufficient to ensurethat said tilting takes place regardless of the ground encountered, asmentioned above, unless it is acceptable for the anchor to rise acertain distance up its hole until friction makes it possible to obtaina tilting torque, merely because the back of the wing unit has had thegood luck to come into abutment. That offset is due to the need to leaveempty the penetration axis of the anchor in the ground so that thedriving rods can pass freely, and various solutions have been proposedsuch as those mentioned in the introduction for causing tilting to takeplace, showing clearly that the moment of the above-mentioned forces isindeed considered to be insufficient, but those solutions have not givensatisfactory results to date.

In contrast, the results obtained by the elements of the presentinvention make it possible to achieve pre-tilting automatically,immediately, and irreversibly, thus placing the anchor immediately intothe abutment position, said abutment being achieved by means of theadditional fin and the rear portion of the wing unit, with it beingcertain that there will be little or no raising of the anchor.

Also, adding another fin symmetrically disposed to the first and on theother side of the plane of the wing unit serves to protect the anchorline situated behind it, and simultaneously assists in providingguidance while the anchor is being driven into the ground.

The embodiment shown in FIG. 8 below, which has a rigid traction linethat may be a single piece between the attachment point and the surface,serves to avoid the need to socket and secure a cable or otherdeformable line to an anchor piece and/or a linking piece for engagingthe anchor, thereby reducing manufacturing costs.

In that embodiment, the existence of a spring enclosed in the body ofthe anchor and bearing against the end of the anchor line makes itpossible, when so decided and then immediately, to obtain pre-tilting ofsaid anchor and to accompany the tilting thereof to an angle of about30°, thereby making it possible to obtain in irreversible manner theengagement of the rear of the wing unit in the ground at a determinedand desired depth, which is particularly necessary when operating atshallow depth in the ground and when it is desired to obtain optimumresistance to traction; the movement is then independent of the shape ofthe anchor which means that the anchor can be given a shape that is morefavorable to penetration into the ground.

Other advantages of the present invention could be mentioned, but thosegiven above suffice to demonstrate the novelty and the advantagesthereof. The following description and figures show embodiments of theinvention but they are not limiting in any way: other embodiments arepossible in the context of the scope and the extent of the invention, inparticular by changing the shape of the body of the anchor which may bemade either from mechanical pieces that are assembled together andwelded or else out of pieces that are cast or forged, or indeed out ofother materials, etc. . . . .

FIG. 1 is an overall perspective view of an embodiment of a groundanchor device of the invention.

FIG. 2 is a longitudinal section view of a FIG. 1 device.

FIG. 3 is a simplified view of the same device as shown in FIG. 2.

FIG. 4 is a section view on CC' of the FIG. 3 device.

FIG. 5 is a longitudinal section view of another embodiment of a deviceof the invention.

FIG. 6 is a cross-section view on DD'0 of the FIG. 5 device.

FIG. 7 shows the various stages of tilting when implementing a device asshown in FIGS. 1 to 6.

FIGS. 8 to 10 show another embodiment of a device of the invention: FIG.8 is a longitudinal section view on VIII-VIII' of the plan view of FIG.10, while FIG. 9 is a section view on IX-IX' of FIG. 8.

FIGS. 11 and 12 show how the device of FIGS. 8 to 10 operates in use.

The device for anchoring the foundation of a structure in the groundcomprises in conventional manner a ground anchor 1 and a traction line8, where traction is applied on axis ZZ'.

The body of the anchor 1 is constituted by various elements including inparticular a front wing unit 2 shaped to penetrate into the ground andwhich may be constituted by two wings cut to an end point andsymmetrically disposed on either side of the plane defined by the axisof the traction line ZZ' and the penetration direction XX' of theanchor: said shaped front wing unit 2 thus enables the anchor to bedriven into the ground along said axis XX' by thrust from a driverelement 27 (FIG. 11) which is applied from the surface of the ground orfrom the surface of the wall of the terrain into which said anchor is tobe caused to penetrate, and which is received on the axis XX' in theback of the anchor in a housing 4 provided for that purpose. Said anchorbody also includes, on either side of said housing 4, a rear wing unit 3extending the front wing unit 2 and of sufficient area to enable it toopposite the effect of traction from the line 8 when in the anchoringposition by coming into abutment in the ground as shown in FIG. 7 afterthe anchor has penetrated therein and after an initial tilting step,said abutment being represented by the force F'2 in FIG. 7, with thefront wing unit 2 then also providing reaction on the other side of theaxis ZZ' by coming into abutment in the ground and applying force F'3:it is the combination of these two reaction forces in the ground thatmake it possible to ensure that the anchor is balanced and that thetraction line 8 subjected to the desired traction force T4 after theanchor has been put into place at the desired depth is indeed retained.

The tip of one of the ends 18 of the traction line 8 is secured to anattachment piece or point situated towards the middle of the body of theanchor 1, with said attachment point 9 being necessarily offset from thetraction axis ZZ' thereof towards the axis XX' of the body of the anchor1 in the embodiments of FIGS. 1 to 7, and even being preferably situatedon said axis so as to obtain as great a tilting torque as possible,whereas in the embodiments of FIGS. 8 to 12, the offset need not existor may at least be smaller since the desired and necessary tiltingtorque is then provided by the power of the compression spring 24.

In FIGS. 1 to 7, said guide and bearing piece 7 is integral with thebody of the anchor 1 and has said end 18 of the traction line bearingthereagainst, which line is then necessarily deformable, e.g. being acable, with a cable being taken as the reference in the remainder of thedescription of FIGS. 1 to 7, said end 18 being fixed to said attachmentpoint 9: the guide and bearing piece 7 enable the end 18 of the tractionline 8 to be guided between said attachment point 9 and the tractionaxis ZZ' proper, thereby ensuring the said offset and being of a formsuch that said end 18 of the traction cable 8 forms an angle β of morethan 10° and less than 90° relative to the axis XX' of the anchor, andpreferably lying in the range 60° to 90°.

In the embodiment of FIG. 2, or of FIG. 3, or of FIG. 4, said attachmentpiece or point 9 is constituted by a hinged endpiece whose shape in thiscase is circularly cylindrical, at least about an axis perpendicular tosaid axes XX' and ZZ', being fixed to and secured to the tip 19 of theend 18 of the cable 8 on which it is socketed: said endpiece 9 can thusbe a piece that is cylindrical or a piece that is spherical: it may alsobe a fastener in the body of the anchor; the piece constituting theendpiece 9 may have a hollow appendix in which there passes the end 18of the cable 8: in which case it is the appendix that bears against theguide piece 7 of the body of the anchor. Said endpiece 9 is housed andhinged in a housing 10 of the body of the anchor in which it is capableof pivoting at least about an axis perpendicular to said axes XX' andZZ' and in communication with a flared orifice 20 through which said end18 of the cable passes. Said housing is preferably situated in front ofthe center of the surface of the wing unit 2, 3 of said anchor, taken asa whole.

As can be seen in FIG. 2, when pulling along the axis ZZ' with a force Ton the traction and anchor line 8, said force is transmitted at the end18 of said traction cable 8 to the attachment point or endpiece 9 alongan axis YY' which is at an angle a to the axis ZZ', such that when theanchor is in its original, pre-tilting position, e.g. when the anchor isat the bottom of the hole, said angle α is equal to the above-definedangle β.

The combination of the traction force T and the reaction force R1generated by the endpiece 9 to oppose transmission of said traction tothe end 18 of the cable, creates a resultant force R extendingtransversely to said axes XX' and ZZ', thus creating an immediatetilting torque due to the thrust of the end 18 of the traction line 8 onthe bearing piece 7: the inclination of the reaction force R naturallydepends on the initial angle β; it is preferable to use an angle in therange 60° to 90°, but even a very small angle of the order of 10° wouldstill provide a reaction force; the maximum value for the angle is 90°since beyond that, a greater angle would create a tilting force that wasof no use during anchoring proper of the anchor in its final position inthe ground in which it is to remain, and could possibly even beunfavorable for a prestress effect on the ground in which it isdesirable to obtain symmetrical distribution of the wing units withoutany additional tilting force.

Said body of the anchor 1 may also include a protective fin 5 in frontof said bearing piece 7 to protect both it and the cable while theanchor is being driven into the ground, the fin extendingperpendicularly to the plane of the front wing unit 2 over a height hrelative thereto that is greater than the distance d of the offset ofthe axis ZZ' of said traction cable 8, and the body of the anchor 1 mayalso include a fin 6 situated on the other side of the plane of thefront wing unit 2 relative to said first fin 5.

Said two fins 5 and 6 are preferably symmetrical about the plane of thewing unit 2 and identical so as to balance forces while the anchor isbeing driven, thus, in combination with the front wing unit 2, ensuringthat driving takes place in the intended direction.

As shown in FIG. 7, said fin 5 or top rib has a tapering front end toenable it to penetrate into the ground, to cut the ground and protectthe cable 8, whereas the fin 6 or bottom rib, likewise having a taperingfront end of the same kind, cuts the ground in the same manner as thetop rib, and additionally, by means of its heel, constitutes a tiltingabutment, as shown in FIG. 7.

FIG. 3 thus shows the FIG. 2 device in section AA' (see FIG. 4), whileFIG. 4 shows the same device in section on CC' of FIG. 3: in this casethe housing 10 for the endpiece 9 is cylindrical in shape.

As shown in FIGS. 5 and 6, the tip 19 at the end 18 of the cable 8 canbe socketed directly in a housing 17 of the body of the anchor 1, andsaid bearing piece 7 can extend beyond the zone in which it bearsagainst the end of the cable 8 at 90° to the axis XX' into said housing17 so as to co-operate therewith to constitute said attachment point 9.

FIG. 7 shows three positions of the anchor after it has been put intoplace, e.g. by pile-driving, so as to leave behind it a borehole 15 ofaxis PP' in the ground 11 through which it has been driven to thedesired depth from which it will then tilt, with the stroke required fortilting being known; depending on the type of ground, said stroke mayconstitute half the length of the anchor. A small amount of slippingtakes place due to the ground compacting around the anchor. Throughoutthe stage during which the anchor is being driven, the axis PP' of theborehole 5 coincides with the axis XX' of the anchor.

The first step is a pre-tilting step, that is immediate and irreversibleand that takes place as soon as tension is applied by the anchor line orcable 8 being subjected to the force T2, with this tilting being due tothe resultant of the parallelogram of action and reaction forces shownin FIG. 2. By way of example, the following values may be given to theresultant force R that performs pre-tilting and then tilting dependingon the angle of the anchor and for a tensioning force T2 which is, forexample, constant and equal to one metric tonne weight: initially, if αor β is 90°, R=1.4 tonnes; then as the angle decreases because oftilting, such as in the position 13 of FIG. 7, for example, to a valueof 60° (which could under other circumstances likewise be a startingposition with α and β equal to 60°), R=10,000 Newtons or about 1 tonne;then in a third step of tilting or in an initial position such as theposition 14 for example with a being equal to 40°, R =6,840 Newtons;thereafter, beyond that point, when α decreases to 20°, the resultant Ralso decreases to 3,480 Newtons, but that is no longer of greatimportance since, under such circumstances, the engagement of the wingunits in the ground, in particular the engagement of the rear wing unit,is sufficient to complete rotation from position 14 to the finalanchoring position.

The force R is thus naturally greater at the beginning of rotationduring the pre-tilting step in which said force, assuming that the angleα is large enough, causes tilting torque to be generated, because of thedistance of said resultant R from the point of rotation G, such that thetorque is large enough to cause the anchor to tilt in the ground,whatever the nature of the ground.

In position 12 of FIG. 7, immediately after pre-tilting, the force T2transmitted by the anchor line continues to generate a force and thus atilting torque on said bearing piece 7 as mentioned above, which forcedecreases progressively as the anchor tilts, i.e. as the angle αdecreases, given that the angle β naturally remains constant all the wayto the end of tilting. Beyond an appropriate angle α, it is the bottomfin 6 that comes into play by forming a bearing and locking point in theground by means of its heel 16, thus creating a reaction force F1 whichopposes upwards movement of the anchor: starting from the resultingposition 12, an additional tilting torque is thus established betweensaid ground reaction force F1 and the traction force T2.

In the subsequent tilting stage 13, during which the heel 16 of thebottom fin 6 disengages and thus decreases the reaction force F'1 in theground, it is the rear wing unit 3 of the anchor that engages fully inthe ground whereas initially only its heel 22 was engaged, therebycreating a significant reaction force F2 which, so to speak, takes overfrom the force F1, F'1 while at the same time the ground reaction forceF3 on the front wing unit also begins to become significant, but of amagnitude that is smaller than the rear force F2 since the effectivearea of the front wing unit in the ground is smaller,-thereby enablingthe anchor to continue to tilt.

The end of tilting, as illustrated by way of example in position 14,occurs when the ground reaction forces F'3 and F'2 come intoequilibrium, thereby also compensating the tension force T4 applied tothe cable 8, relative to the position of the traction point thereof,which is preferably in front of the center of gravity of the surface ofthe anchor, so as to ensure that said equilibrium is stable: the twotorques generated by the two reactions forces in the ground mustcompensate and thus cancel in order to obtain said equilibrium at thedesired final angle for the axis XX' relative to the initialpile-driving axis PP' or the traction axis ZZ' of the cable 8.

As mentioned in the introduction, it is clear that the traction cable 8used in the present description could be replaced by any otherdeformable and/or flexible line enabling traction forces to betransmitted, such as a chain, a belt, or any other apparatus such as adeformable rod.

FIGS. 8 to 12 show another embodiment of the invention whose mainapplication is anchoring at shallow depths, down to about 1 meter, andin which said guide and bearing piece 7 is not integral with the body ofthe anchor as before, but with the traction line 8: it is constituted bya rigid piece forming the end 18 of the traction line 8, and it bearsvia a spring 24 on the body 1 of the anchor, and it is hinged about thepoint 9. Under such circumstances, the traction line proper 8 can be asingle piece all the way to the surface of the ground, and may includethe endpiece 18 and be constituted by a single piece all the way to andincluding the hinge and the attachment point 9; the traction line up tothe surface could also be constituted by a deformable line as in FIGS. 1to 7, and may be fixed in the vicinity of the anchor 1 to the end ofsaid endpiece 18 remote from its attachment point 9, in which case onlythe endpiece 18 is rigid.

Naturally, in this embodiment, the elements described above are still tobe found, such as the main body 1 of the anchor which has a finconstituting a swelling in which the hinge and anchor point 9 issituated, and a fin forming an abutment spur 6 on the other face; therear portion of the body 1 of the anchor has a bore 4 for guiding theend of a pile-driving rod 21, the rear end 22 of the body 1 serving,amongst other things, as an anvil for said pile-driving rod, as shown inFIG. 11. The wing unit of the anchor is of constant section in its rearportion 3 while its front portion 2 is of tapering section to penetrateinto the ground 11 and has two lateral heels 23 that facilitate grippingin the ground when traction T is applied to the anchor line 8; theembodiment shown in FIGS. 11 and 12 corresponds to the same stages asthose described with reference to FIG. 7, and reference can be madethereto, in particular for the pre-tilting positions 12 and 13 in FIG.7.

The shape of such an anchor is designed to provide as small a resistanceto penetration into the ground as possible, even though it is possibleto form lead boreholes prior to driving the anchor into the ground, saidshapes being tapering arrowheads, and all of the elements of the wingunit join the body proper of the anchor via large radiuses of curvature.

A housing 10 is formed in the main body 1 of the anchor in which the endattachment point 9 of the anchor line 8 is engaged, as by a tenon hingeor on an axis or cylindrical stub axle that forms a portion of saidanchor line; said housing 10 opens via an opening 20 to the face of theanchor that may be referred to as its "dorsal" face to allow the rigidpiece 7 at the end 18 of the anchor line 8 to pass and rotate relativeto the anchor, e.g. through about 90°, between a driving position and afinal anchoring position; the anchor line may be threaded therethroughduring assembly via the "ventral" face of the anchor into which saidhousing 10 opens out.

The hinge 9 is situated slightly in front of the center of the surfacearea of the anchor 1, and another bore 25 situated behind said hinge 9contains the spring 24 and can communicate with the bore 4 for thedriving rod: the spring 24 gives a pre-tilting impulse for engaging theanchor while it is being put into place when the driving rod 27 isremoved. Insofar as the entire traction line 8 is rigid all the way tothe surface, this rectifying compression can be maintained from thesurface throughout driving, otherwise, if the traction line isdeformable, at least in part, a stud or any other holding means may besecured to the driving rod 27 to keep the end 18 thereagainst until thedriving rod is withdrawn. The spring 24 is of the coil spring type andit operates in compression: it is well protected from the surroundingmedium 11 during driving since it can be entirely housed within the bore25, which bore is closed at that time by the rigid piece 7 preventingany gravel or other ground particles penetrating, which particles couldimpede expansion of the spring.

By having the end portion 18 of the anchor line curved into an angledshape, it is possible to accommodate the offset between the tractionline ZZ' and the hinge axis 9: this offset can be of use for engagingthe stub axle 9 in the body of the anchor without it being necessary toenlarge it excessively, but it need not be provided given the existenceof the spring 24 which itself provides the tilting torque by means ofits reaction force R. It would even be possible to envisage a rigidtraction line 8 located on and hinged on the driving axis XX': undersuch circumstances, the traction line 8 may itself be used for driving,or else the driving rod 27 is hollow and surrounds the traction line 8;the spring 24 would then be situated in a bore that is offset relativeto the axis XX'.

During testing performed on an anchor that was 200 millimeters long and70 millimeters wide, having a total wing unit area of 105 cm², made ofall-welded steel, weighing about 1.2 kg, with a rigid anchor line havinga strength of about 14,000 Newtons, and with the anchor having astrength of about 30,000 Newtons, immediate tilting was obtained for aspring force of at least 150 Newtons, and it was obtained at the desireddepth and for a nominal anchoring capacity in hard ground of about 7,000Newtons.

We claim:
 1. Device for anchoring the foundation of a structure in theground, the device comprising a ground anchor, including an anchor body,and a traction line having an axis ZZ' for traction along the axis ZZ',said traction line having a tip at an end of the line that is secured toan attachment point that is fixed on the anchor body, said anchor bodyincluding a front wing unit having an axis of XX' and shaped topenetrate into the ground along the axis XX', and a rear wing unit foropposing the effect of traction on said line by coming into abutmentwith the ground after the ground anchor has penetrated therein and hastilted, wherein the device includes guide and bearing means, including aguide piece disposed between said attachment point and the axis ZZ', forguiding and supporting said end of said traction line and fortransmitting to the anchor body a force transverse to the axis ZZ',thereby to create tilting torque when said end is put under tension bythe traction line along said axis ZZ', said front wing unit defining aplane having first and second sides, said guide piece being disposed onthe first side of the plane, said anchor body including a fin situatedon the second side of the plane and including a heel which bears againstand jams in the ground once the traction line is put under tension alongthe axis ZZ' so as to tend to cause the anchor to be raised.
 2. A deviceaccording to claim 1, wherein said guide piece is constituted by a rigidpiece forming the end of the traction line, hinged about the attachmentpoint, and bearing against the anchor body via a spring.
 3. A deviceaccording to claim 2, wherein said rigid piece is angled and has an endthat terminates in stub axles constituting said attachment point of thetraction line.
 4. An anchor device according to claim 1, wherein saidattachment point of the traction line is offset from the axis ZZ'towards the axis XX', said guide piece ensuring said offset and being aportion of the anchor body on which said end of said attachment point ofthe traction line bears, which traction line is deformable.
 5. A deviceaccording to claim 1, wherein said attachment point is constituted by anendpiece in the form of a circular cylinder at least about an axisperpendicular to said axes XX' and ZZ' which endpiece is stationary andsecured to the tip of said end of the traction line and is hinged in ahousing formed in the anchor body in which housing it can rotate.
 6. Adevice according to claim 4, wherein the tip of said end of the line isdirectly socketed in a housing of the body of the anchor, and saidbearing and guide piece extends beyond a bearing zone for the end of theline at 90° to the XX' axis as far as said housing to cooperatetherewith to constitute said attachment point.
 7. An anchor deviceaccording to claim 3, wherein said attachment point is situated on theaxis XX'.
 8. A device according to claim 3, wherein the angle betweenthe end of the traction line and the axis XX' lies in the range 10° to90°.
 9. A device according to claim 1, wherein said anchor includes aprotective fin in front of said guide piece and extendingperpendicularly to the plane of the front wing unit over a height htherefrom that is greater than an offset distance of the axis ZZ' ofsaid traction line.
 10. A device according to claim 9, wherein the finsituated on the second side and the protective fin are symmetrical aboutsaid plane defined by the front wing unit, are identical, and are bothsituated in front of said guide piece.